Mechanical stoker



Nov. 8, 1932. e. E. WHITNEY MECHANICAL STOKER 1929 .5 Sheets-Sheet Filed June 22 Nov. 8, 1932. c. E. WHITNEY MECHANICAL STOKER Filed June 22. 1929 I5 Sheets-Sheet 2 f 71 can for Geozgafi Mil nay Nov. 8, 1932.

E. WHITNEY MECHANICAL STOKER Filed June 22, 1929 3 Sheets-Sheet Patented Nov. 8, 1932 UNITED STATES PATENT OFFICE GEORGE E. WHITNEY, OF BBIDGEPOBT, CONNECTICUT, ASSIGNOB, BY MES NE ASSIGN- IENTS, TO WHITNEY STORED, CORPORATION MECHANICAL STOKEB Application filed June 22,

My invention relates to mechanical stokers, in which the coal is fed and delivered to the firepot by means of what is known as a plunger feed.

The object of the invention is to so construct the plunger that there can be no jamming of the coal such as would block the plunger and consequently stall the motor or cause breakage.

A further object is to properly feed the coal according to the demands of the furnace.

A still further object is to prevent the formation of sulphuric and other acids by the distillation of the coal.

In the accompanying drawings I have illustrated the preferred form of my invention, and the following description is to be read in connection with these drawings in which Figure l is a side elevation of my'improvement Figure 2 is a section at the line 22 of Figure 1 Figure 3 is a section at the line 3-3 of Figure 1 ment- Figures 10 and 11 are respectively sections at the lines 10-10 and 11-'11 of Figure 9, on an enlarged scale, and

Figure 12 is a section at the line 1212 of Figure 1.

Similar numerals of reference denote like parts in the several figures of the drawings.

Various means have been utilized for de-' l'vering coal in underfeed stokers among which are structures that employ a reciprocating plunger and it is to this style of underfeed structures that my invention relates.

In feeding the coal by means of reciprocat- 1929. Serial No. 372,811.

ing plungers, a serious difliculty has heretofore obtained, in that when reliance was placed on the extremit of the plun er for forcing the coal tower the firepot, t e consequence was that quite frequently the fuel would be massed or jammed against the fuel passageway. Plungers made up of shouldered elements equally spaced apart would also fail to properly deliver the fuel.

The present invention overcomes this defeet since the feeding of the coal is effected by a series of shouldered portions distributed at intervals throughout the extent of the plunger, the length of these portions being gradually decreased from the front, or hopper end of the apparatus, to the rear or firepot end of the same, so that, after the fuel passageway has within it a considerable amount of coal, the feedin of the latter will be accomplished throug out the length of the plunger; moreover, since there are more of these shouldered ortions at the rear or firepot end of the piimger, within a given distance, than there are at an other part of the plunger within the same istance, it will be understood that ample coal will be fed by that portion of the plunger that is nearest-the firepot and the massing of the coal prevented throughout the length of the plunger.

This is a decide since heretofore feedin plungers that have shouldered portions, fe the coal equally as fast throughout the entire length of the plunger, and the binding of the coal against the walls of the fuel passageway was sooner or later inevitable.

The plunger of my apparatus may be of any suitable shape in cross section, such as round, triangular or square, and such plunger has a much smaller cross sectional area than that of the fuel passageway, and the shoul dered portions are all of the same diameter, although a small variation in this res ect is immaterial, but I prefer to use a unger that has a general triangular shape in cross lunger preferred since the coal shdes down the sides improvement in the art.

thereon on all occasions, and, moreover, a plunger of this shape can pass more readily through coal withm the fuel passageway. Also, the shouldered portions preferably incline upwardly and forwardly, so that an excess of coal may be thrown upwardly therefrom, and also for the further reason that this construction tends to keep the curved bottom portion of the plunger against the fuel passageway.

1 denotes the bed or frame of the apparatus, as well as all parts rigid therewith, having legs 2 which carry rollers 3 so that the apparatus may be readily moved.

1 is the coal hopper secured to the bed and 5 is the firepot constructed and secured in the manner hereinafter to be described. 6 is a closed fuel passageway or conduit which is cylindrical in shape and leads from the hopper to the firepot. The firepot is of the conventional shape, and is preferably made in sections having numerous perforations 7 therethrough, and the outer upper edge of the firepot has a flange 8 which rests upon a ring 9, the latter secured to the frame of the apparatus.

This manner of supporting the firepot is quite 0rdinary,and as the firepot tapers downwardly, it will be clear that an air space 10 will be provided between the ring and the firepot, so that air may readily pass from this space through the coal to support combustion. I

Surrounding the conduit 6 is an air chamber or jacket 11 secured at its front end. or the end nearest the hopper within a housing 12 that is ri 'd with the bed, the rear end of this charm er being secured to the firepot or to any suitable part of the frame of the apparatus, so as to communicate directly with the air space 10. v

13 is an electric motor fixed on the bed 1,

and 14 is a blower likewise fixed and oper-- ated in the usual manner by the motor and having a conduit 15 which leads into the housing 12, and therefore in direct communication with the front end of the air chamber 11.

1 The air from this blower has two functions, first, to create a forced draft through the coal that is in the firepot, and second, to constantly act to keep the passageway 6 comparatively cool.

In the description heretofore given and in that which follows, by the term rear I mean in the direction of the firepot, and by the term front is meant in the direction of the hop sectional area.

floor of the conduit 6 and partly on the bed 1 of the apparatus, and such plunger is made up of a series of shouldered portions 18 that are generally triangular in shape, all of which portions have substantially the same cross These shouldered portions are integral parts'of the plunger 17 and such portions are formed by inclining the sides of successive shouldered portions forwardly and inwardly, and the plunger as a whole has a circular shaped lower portion as shown at 19.

The lengths of these shouldered portions are quite material and such lengths gradually decrease from the front toward the rear, and the sides of these triangular shaped shouldered elements of the plunger are preferably inclined from the bottoms forwardly toward the hopper, as shown at 20, the object of these inclines being to cause any surplusage of coal to be thrust upwardly so as not to be acted upon directly by the shouldered portions, since, otherwise, there might be a choking of the coal supplied to the firepot. Also, the action of these inclines in thrusting the coal upwardly tends to keep the bottom of the plunger down against the bottom portion of the conduit 6.

The shoulders 18 at the front of the plunger have a greater incline with respect to the vertical than the shoulders throughout the rest of the plunger, in order that more or less coal resting upon these inclines may be moved upwardly out of the path of the shoulders as the plunger commences its rearward stroke to feed the coal to the firepot. It will be observed that the described arrangement of shoulders on the plunger provides progressively increasing pushing surface as the firepot end of the plunger is approached, so that the coal is fed more rapidly as it approaches the firepot,'and all tendency of the coal to back in the tube is avoided.

Extending from the rear end of the apparatus and fixed in the frame is an outlet passage 21 which communicates directly with the air space 10, and within this pipe is an ordinary butterfly valve 22 fixed to a shaft 23 that is journaled within this pipe, the function and operation of which will be presently explained.

The forward extremity of the plunger terminates in a plain block 24 which is guided on the bed 1, and as the plunger operates within the closed conduit 6 more or less coal will be forced rearward toward the firepot this depending upon the stroke of the plunger which stroke is regulated in the manner presently to be set forth, and therefore it will be clear that quite a lot of coal will always remain in this conduit the consequence being that, as more coal is 'fed from the hopper there is always an ample amount to be engaged by the shouldered portions of the plunger, and as this coal is delivered within the bottom of the firepot the amount of coal within the latter will gradually increase until 1t'1s substantially level with the top of the firepot and thereafter the feeding of the coal is regulated according to the consumption of the latter.

The shaft 25 of the motor 13 carries a worm 25 which meshes with a worm wheel 26 fixed on a shaft'26 suitably journaled to the bed 1 and this shaft carries a small spur pinion 27 that is in mesh with the large gear 28 which latter as well as a crank disk 28 is fixed on a shaft 27 that is journaled to the frame 1, and this disk 28 carries a crank pin 29 around which is pivoted a rod 30 which extends toward the front of the apparatus.

The front end of the rod 30 is pivoted at 31 to the lower end of a beam 32 whose upper end is pivoted to a plunger link 33, and this beam midway of its length is pivoted at 34 to the upper end of a swingable arm 35 whose lower end is pivoted to the frame of the apparatus at 36.

This pivoting of the connecting beam 32 to a swingable member constitutes what may be called a floating fulcrum which is carriedforward and backward by the reciprocating movements of the rod 30, and therefore it is necessary that stops be provided to arrest the movements of this arm 35 between certain limits, in order that the reciprocations of the rod 30 may effect reciprocations of the plunger link 33 so as to bring about the desired movements of-the plunger 17, and accordingly the operation of this beam will now be described.

37 is a part of the stationary frame which acts as a stop to limit the forward throw of the arm 35.

It will be evident that when the rod 30 is moved forwardly, the end of the arm 35 will be swung toward the stop 37, and during this movement the plunger link 33 will be stationary, but as soon as the arm 35 contacts this stop 37 the beam 32 will be converted into a lever of the first class and the continued forward movement of the rod 30 will cause the plunger link 33 to drive the plunger 17,,rearward, and it will. thereforebe clear that the nearer the arm 35 is to the stop 37 at the initial forward stroke of the rod 30,; the longer will be the rearward or feeding stroke of the plunger. Since the stop 37 is stationary, an adjustable stop 38 is provided which is preferably a curved member of suitable length that terminates the free end of a short lever 39 that is pivoted at 40 to the frame. and the position of this lever is determined by means of a hand lever 41 pivoted at 42 to the upper part of the frame, the rear end of this lever 41 being connected to the stop 38 by means of a link 43 whose ends are pivoted at 44, 45, to the lever 41 and stop .38

respectively.

When the rod 30. after the end of its forward movement, which effects the rearward or feeding movement of the plunger 17, as

above set forth and as is shown at Figure'*5, begins to moverearwardly it will carry the arm 35 away from the stop 37 and there will be no movement of the plunger'17 until said arm contacts the stop 38 and thereafter the the stop 38 further from the stop 37, which will, of' course, increase the idle movement of the arm 35, and consequently lessen the effective stroke of the plunger. By pulling the lever 41 upwardly to its limit, the stop 38 will be thrown forwardly so that the free end of the arm 35 will be closely confined between the stops, which will effect the maximum stroke of the plunger.

When the plunger has been moved forwardly one or more of the shouldered portions 18 at the front end of the plunger will be immediately beneath the hopper, according to the extent to which the plunger is operated, but it is sufficient if only one of these shouldered portions is in such position below the hopper so that coal from the latter will drop in front of such portion, and on the rearward stroke of the plunger such shoulder will carry the coal into the passageway, and thereafter the successive reciprocations of the plunger will keep delivering the coal within the passageway so that such coal will be engaged by the other shoulders and carried rearward toward the firepot until finally there will be enough coal in the passageway so that all the shouldered'portions will cooperate in carrying the fuel toward the firepot.

The coal within the passageway is constantly fed rearward by the action of these various shouldered portions, and the feeding effect is greater as the coal approaches the firepot, owing to the decreasing lengths of the shouldered portions as above described, and therefore there can be no jamming of the fuel in the passageway, such as might stall the motor, or cause breakage of parts. In, other words, the resistance to the feed of the coal is less at the firepot end, since there are more shouldered elements at this end of the plunger, and therefore the work is sub-divided and the coal is moved at this end more easily. Therefore,.the stroke of the plunger feeder can be very limited and there is no danger of any wedging of the coal.

After the apparatus has been working for a while, the delivery of the coal may be regulated in the manner hereinbefore set forth.

As fast as the consumed coal turns to ashes at the upper surface of the firepot, the crowd ing of the fuel into the firepot at the bottom will cause these ashes to fall over the edge of the firepot into any suitable receptacle (not shown).

46 is a crank arm fixed to the shaft 23, and pivoted at 47 to the lower end of this crank arm is a long connecting rod 48, the other end of the latter being pivoted at 49 to the lower extremity of a bracket 50 that is fixed to the hand lever 41, and it will be clear that when the outer end of this lever is elevated to its limit. and the plunger stroke increased to furnish the greatest amount of coal to the firepot, as hereinbefore described, the valve 22 will be closed because at that time the full benefit of the air supplied from the blower is needed to create a maximum forced draft through the coal in the firepot.

On the other hand, when this lever 41 is depressed to its limit the valve 22 will be opened because at-that time the stroke of the plunger is at its minimum, and it is not ad-,

visable that there should be any forced draft to speak of through the coal in the firepot,

and accordingly, in this instance, the air from the blower will be mainly discharged through the outlet passage 21.

lhe cooling air jacket 11 is used around the coal feeding conduit since gas forms when the furnace is choked off after a hot fire by heat coming back, and sulphuric acid is then generated which attacks the metal parts with bad results. The air cools the coal and prevents this, and the outlet for this air is at the rear or far end of the air space which surrounds the firepot and is substantially in direct line with the length of the jacket.

There is always the same amount of air supplied from the blower within the cooling jacket 11, and therefore the benefits of the cooling of the passageway for the coal are always present, and it is impossible for any disadvantages, such as the formation of sulphuric and other acids, to result from the distillation of the coal.

It will therefore be clear that this valve 22 will be opened more or less when the stroke of the plunger is not at its maximum, and it follows that the draft of air through the coal in the firepot is automatically regulated by the operation of the hand lever 41, or, in other words, is regulated by the means employed to regulate the amount of coal fed to the firepot.

The object of the legs and the wheels is to enable the apparatus to be easily moved to any desired position to locate the firepot, but,

of course, theselegs may be dispensed with.

3. A construction as in claim 1 in which the fuel engaging faces are inclined rearwardly.

4. An underfeed furnace, comprising a hopper, a perforated firepot, a fuel passageway leading from'the hopper to the firepot,

a single plunger within said passageway and hopper provided with shoulders having faces arranged transversely of the plunger which faces are adapted to engage the fuel and are spaced apart by distances that decrease from the end of the plunger near the hopper to the end of the plunger near the firepot, an air jacket surrounding said passageway and fire pot, an outlet leading from said air jacket to the rear of the fire pot, a valve arranged to control said outlet, a blower communicating with'said jacket near the hopper, a motor, means for transmitting motion from the motor to the plunger to reciprocate the same, and means for simultaneously regulating the stroke of the plunger and the position of said valve.

5. A construction as in claim 4, further distinguished by the inclusion of means for operating said valve and causing the air to be discharged through the firepot or through the outlet without interrupting the supply of air throughout the air jacket.

6. In an underfeed furnace having a fire pot and a receptacle for coal, the combination with means forming a tubular passageway from said receptacle to said fire pot, of a feed plunger having faces adapted to engage the coal to feed the same, said face. being arranged to provide increasing feeding area toward the fire pot end of the plunger, whereby the coal is fed at a rate which increases progressively as the fire pot end of the passageway is approached.

7. In an underfeed furnace having a fire pot and a receptacle for coal, the combination with means forming a tubular passageway from said receptacle to said fire pot, of

a plunger for moving coal through said passageway, said plunger being provided with progressively increasing pushing surface as the fire pot end thereof is approached.

8. In an underfeed furnace having a fire pot and a receptacle for coal, the combination with means forming a tubular passageway from said receptacle to said fire pot, of a feed plunger, said plunger being provided with faces extending transversely' of the plunger and adapted to engage the coal to feed the same, the total area of said faces per unit of length of the plunger increasing progressively from the receptacle to the tire pot, and means to reciprocate said feed plunger. 1

' 9. A11 underfeed furnace, comprising a hopper, a perforated fire pot, a fuel passageway leading from the hopper to the fire pot, a feed plunger within said passageway, an air jacket surrounding said passageway and fire pot, an outlet leading from said air jacket in the rear of the firepot a valve arranged to control said-outlet, a lilower communicating with said jacket near the hopper,

a motor, means for transmitting motion from the motor to the plunger to reciprocate the same, and means for simultaneously regulating the stroke of the plunger and the position of said valve.

In testimony whereof I afiix my signature hereto.

GEORGE E. WHITNEY 

